A human tower under construction in Spain

Members of the Colla 'Caprogossos de Mataro' climb up as they construct a human tower during the 24th Tarragona Castells Comptetion on Oct. 7, in Tarragona, Spain. The 'Castellers' who build the human towers with precise techniques compete in groups, known as 'colles', at local festivals with aim to build the highest and most complex human tower. The Catalan tradition is believed to have originated from human towers built at the end of the 18th century by dance groups and is part of the Catalan culture.

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Members of the Colla 'Capgrossos de Mataro' start a construction of a human tower during the 24th Tarragona Castells Comptetion on Oct. 7, in Tarragona, Spain.

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Members of the Colla 'Vella de Valls' start a construction of a human tower during the 24th Tarragona Castells Comptetion on Oct. 7, in Tarragona, Spain.

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Members of the Colla 'Vella de Valls' climb up as they construct a human tower during the 24th Tarragona Castells Comptetion on Oct. 7, in Tarragona, Spain.

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Members of the Colla 'Jove de Tarragona' start a construction of a human tower during the 24th Tarragona Castells Comptetion on Oct. 7, in Tarragona, Spain.

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Members of the Colla 'Vella de Valls' celebrate after building a human tower during the 24th Tarragona Castells Comptetion on Oct. 7, in Tarragona, Spain.